Manned aircraft, unmanned aerial vehicles (UAVs) as well as satellites are often used for aerial surveillance, mapping and/or the like. These platforms usually carry sophisticated photography equipment, used for capturing still photographs and/or video sequences (hereinafter jointly referred to as “imagery”) of the earth's surface.
Geo-referencing the captured imagery is an important process, involving the association of each piece of imagery with its real-world geographic location. For example, when the imagery is a video sequence, the geo-referencing may include a determination of the geographic coordinates of the four corners of frames in the video. The utility of the imagery without this association is doubtful, since the geographic location of various objects of interest appearing in the imagery will remain unknown.
The geo-referencing process commonly involves calculations made based upon data received from a navigation component of the platform, such as its GPS (Global Positioning System) component, as well as from its onboard inertial navigation system (INS). These data are often captured simultaneously with the imagery, and are operatively coupled to it in the form of metadata. For example, an aerial video stream may have coupled to it a stream of metadata indicative of the platform's location and INS parameters at the time of capture.
To perform accurate geo-referencing, the calculations are sometimes aided by a digital terrain model (DTM) which indicates the elevation of the earth and optionally of man-made structures. Other data vastly used for the geo-referencing includes orthophotos, which were previously geo-referenced and corrected to account for camera lens distortion.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.